Using Electro-magnetically Induced Transparency in Photonic Crystal Cavities to Obtain Large Non-linear Effects

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FIG. 1A is a schematic diagram of an EIT system;FIG. 1B is a graph illustrating absorption as a function of ωp when ωc is present; FIG. 1C is a graph illustrating the refractive index as observed by ωp as a function of ωp;FIG. 2 is a schematic diagram of a photonic crystal all-optical switch at 100% resonant linear transmission;
Professor John Joannopoulos
Research Laboratory for Electronics, MIT
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Professor Marin Soljacic
Research Laboratory for Electronics, MIT
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Lene Hau
Harvard Physics Department
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Jim Freedman
MIT Technology Licensing Officer - Chemicals, Instruments, Consumer Products
Patent Protection

Using electro-magnetically induced transparency in photonic crystal cavities to obtain large non-linear effects

US Patent 7,031,585
Enhancement of nonlinear effects using photonic crystals
Nature Materials , 211 - 219 (2004)


This invention can be used in nanophotonics, telecommunication, all-optical computing, and quantum computing.

Problem Addressed

All optical signal processing requires devices that are ultrafast and operate at telecommunication power levels. There is a need for optical devices that can fulfill the requirements in size, switching time and operating power of practical integrated optical systems.


This invention utilizes a solid-state-based electromagnetically induced transparency (EIT) as the non-linear medium in photonic crystal cavities. This increases the non-linear properties of the photonic crystal because EIT is a superb non-linear medium and photonic crystal cavities are optimal structures with respect to maximizing non-linear effects.  Consequently, optical devices designed with this process has unprecedented non-linear sensitivity, with operating power requirements many orders of magnitude smaller than in most non-linear optics devices.


  • Improved the performance of nonlinear optical devices such that the corresponding operation powers and switching times are suitable for implementation in realistic, ultrafast integrated optical devices
  • Enables the miniaturization of optical devices without affecting the operating power requirements